Conventionally, a briquetting machine is used as one of the roll press type forming machines for compressing and forming powdery material. The briquetting machine comprises a pair of rolls, and a hopper for supplying powdery material to the pair of rolls. The pair of rolls comprises a fixed rotary roll and a movable rotary roll that is pressed toward the fixed rotary roll by a hydraulic cylinder. The hopper is disposed above the pair of rolls and comprises a feeding screw that compresses and feeds the powdery material to the pair of rolls. The powdery material that is compressed and fed by the feeding screw is formed into briquettes by the pair of rolls. (See Patent Document 1.)                Patent Document 1: Japanese Patent Laid-open Publication No. H9-192896By using the conventional briquetting machine that has the technical features explained in the above paragraph, it has been tried to compress powdery material and to form it into tablets that have high dimensional accuracy and no burrs. However, when the conventional briquetting machine is used for forming the tablets, the tablets are formed with a sheet-like portion as shown in FIG. 4. Thus, the tablets must be separated from the sheet-like portion by any well-known means. However, as shown in FIG. 5, the burrs remain around the tablets after separating the tablets from the sheet-like portion. Thus, there is a problem in that no product that is to be used as a tablet can be produced.        